Chemical properties of antiepileptic drugs (AEDs)

Chronic Treatment with Oxcarbazepine Attenuates Its Anticonvulsant Effect in the Maximal Electroshock Model in Mice

The objective of this study was to assess the impact of acute and chronic treatment with oxcarbazepine on its anticonvulsant activity, neurological adverse effects, and protective index in mice. Oxcarbazepine was administered in four protocols: once or twice daily for one week (7 × 1 or 7 × 2) and once or twice daily for two weeks (14 × 1 or 14 × 2). A single dose of the drug was employed as a control. The anticonvulsant effect was evaluated in the maximal electroshock test in mice. Motor and long-term memory impairment were assessed using the chimney test and the passive avoidance task, respectively. The concentrations of oxcarbazepine in the brain and plasma were determined via high-performance liquid chromatography. Two weeks of oxcarbazepine treatment resulted in a significant reduction in the anticonvulsant (in the 14 × 1; 14 × 2 protocols) and neurotoxic (in the 14 × 2 schedule) effects of this drug. In contrast, the protective index for oxcarbazepine in the 14 × 2 protocol was found to be lower than that calculated for the control. No significant deficits in memory or motor coordination were observed following repeated administration of oxcarbazepine. The plasma and brain concentrations of this anticonvulsant were found to be significantly higher in the one-week protocols. Chronic treatment with oxcarbazepine may result in the development of tolerance to its anticonvulsant and neurotoxic effects, which appears to be dependent on pharmacodynamic mechanisms.

Neuroprotective Properties of Antiepileptics: What are the Implications for Psychiatric Disorders?

Since the discovery of the first antiepileptic compound, increasing attention has been paid to antiepileptic drugs (AEDs), and recently, with the understanding of the molecular mechanism underlying cells death, a new interest has revolved around a potential neuroprotective effect of AEDs. While many neurobiological studies in this field have focused on the protection of neurons, growing data are reporting how exposure to AEDs can also affect glial cells and the plastic response underlying recovery; however, demonstrating the neuroprotective abilities of AEDs remains a changeling task. The present work aims to summarize and review the literature available on the neuroprotective properties of the most commonly used AEDs. Results highlighted how further studies should investigate the link between AEDs and neuroprotective properties; while many studies are available on valproate, results for other AEDs are very limited and the majority of the research has been carried out on animal models. Moreover, a better understanding of the biological basis underlying neuro-regenerative defects may pave the way for the investigation of further therapeutic targets and eventually lead to an improvement in the actual treatment strategies.

Research Status, Synthesis and Clinical Application of Antiepileptic Drugs

According to the 2017 ILAE's official definition, epilepsy is a slow brain disease state characterized by recurrent episodes. Due to information released by ILAE in 2017, it can be divided into four types, including focal epilepsy, generalized epilepsy, combined generalized, and focal epilepsy, and unknown epilepsy. Since 1989, 24 new antiepileptic drugs have been approved to treat different types of epilepsy. Besides, there are a variety of antiepileptic medications under clinical monitoring. These novel antiepileptic drugs have plenty of advantages. Over the past 33 years, there have been many antiepileptic drugs on the mearket, but no one has been found that can completely cure epilepsy. In this paper, the mentioned drugs were classified according to their targets, and the essential information, and clinical studies of each drug were described. The structure-activity relationship of different chemical structures was summarized. This paper provides help for the follow-up research on epilepsy drugs.

Anticonvulsant Classes and Possible Mechanism of Actions

Epilepsy is considered one of the most common neurological disorders worldwide; it needs long-term or life-long treatment. Despite the presence of several novel antiepileptic drugs, approximately 30% patients still suffer from drug-resistant epilepsy. Subsequently, searching for new anticonvulsants with lower toxicity and better efficacy is still in paramount demand. Using target-based studies in the discovery of novel antiepileptics is uncommon owing to the insufficient information on the molecular pathway of epilepsy and complex mode of action for most of known antiepileptic drugs. In this review, we investigated the properties of anticonvulsants, types of epileptic seizures, and mechanism of action for anticonvulsants.

Management of acute carbamazepine poisoning: A narrative review

Standard management protocols are lacking and specific antidotes are unavailable for acute carbamazepine (CBZ) poisoning. The objective of this review is to provide currently available information on acute CBZ poisoning, including its management, by describing and summarizing various therapeutic methods for its treatment according to previously published studies. Several treatment methods for CBZ poisoning will be briefly introduced, their advantages and disadvantages will be analyzed and compared, and suggestions for the clinical treatment of CBZ poisoning will be provided. A literature search was performed in various English and Chinese databases. In addition, the reference lists of identified articles were screened for additional relevant studies, including non-indexed reports. Non-peer-reviewed sources were also included. In the present review, 154 articles met the inclusion criteria including case reports, case series, descriptive cohorts, pharmacokinetic studies, and in vitro studies. Data on 67 patients, including 4 fatalities, were reviewed. Based on the summary of cases reported in the included articles, the cure rate of CBZ poisoning after symptomatic treatment was 82% and the efficiency of hemoperfusion was 58.2%. Based on the literature review, CBZ is moderately dialyzable and the recommendation for CBZ poisoning is supportive management and gastric lavage. In severe cases, extracorporeal treatment is recommended, with hemodialysis as the first choice.

Efficacy and safety of vigabatrin in patients with tuberous sclerosis complex and infantile epileptic spasm syndrome: a systematic review

INTRODUCTION

Tuberous sclerosis complex (TSC) is a common genetic cause of epilepsy. Infantile epileptic spasm syndrome (IESS) is often the presenting neurologic feature, progressively evolving into refractory epilepsy. Vigabatrin (VGB) is often used in clinical practice as a first-line therapy in TSC with IESS. This systematic review aims to collect and analyze the efficacy data about VGB in TSC cases with IESS, in order to evaluate the strength of evidence in the literature.

METHODS

A systematic search of trials, observational studies, and case series involving patients with TSC and IESS treated with VGB was performed using MEDLINE, CENTRAL, and the US NIH Clinical Trials Registry. Single case studies, animal and non-English language studies were excluded. Seventeen studies were selected, of which 3 were RCTs and 14 were observational studies.

RESULTS

An overall response rate of 67% (231/343 responders) resulted from the analysis, with a spasm-free rate restricted to RCTs of 88% (29/33 subjects).

CONCLUSIONS

Although all the studies analyzed reported beneficial effects of VGB in TSC patients with IESS, with higher response rates in comparison to non-TSC subjects with IESS, a low level of evidence and high heterogeneity do not guarantee sufficient strength for therapeutic recommendations.

Effect of Environmental Concentration of Carbamazepine on the Behaviour and Gene Expression of Laboratory Rats

Carbamazepine (CBZ), an effective drug for epilepsy and other neurological diseases, and its metabolites are one of the most frequently detected substances in the aquatic environment. Although these are doses of very low concentrations, chronic exposure to them can affect the physiological processes of living organisms. This experiment may clarify if carbamazepine, under an environmental and a therapeutic concentration, can affect the behaviour of higher vertebrates, especially mammals, and gene expressions of Ugt1a6 and Ugt1a7 in the brain compared to the control group without exposure to CBZ. Three groups of thirteen rats were randomly formed, and each group was treated either with carbamazepine 12 mg/kg (therapeutic), carbamazepine 0.1 mg/kg (environmental), or by 10% DMSO solution (control). The memory, anxiety, and social behaviour of the rats were assessed by the test Elevated Plus Maze, the novel object recognition test, and the social chamber paradigm. After testing, they were euthanised and brain tissue samples were collected and analysed for mRNA expression of Ugt1a6 and Ugt1a7 genes. The tests did not show significant differences in the behaviour of the rats between the groups. However, there were significant changes at the gene expression level of Ugt1a7.

Comparison of the probability of four anticonvulsant mood stabilizers to facilitate polycystic ovary syndrome in women with epilepsies or bipolar disorder-A systematic review and meta-analysis

Background

Patients treated with anticonvulsant mood stabilizers have a higher incidence of polycystic ovary syndrome (PCOS). However, there is no comparison between different anticonvulsant mood stabilizers. The purpose of this study was to systematically evaluate the prevalence of PCOS in women taking anticonvulsant mood stabilizers and compare the probability of PCOS caused by different anticonvulsant mood stabilizers.

Methods

Five databases, namely PubMed, Embase, Web of Science, Cochrane Library, and Clinical Trials, were searched for literature on anticonvulsant mood stabilizers and PCOS published up to October 28, 2022. This meta-analysis was performed using Revman 5.4, Stata 14.0, and R4.1.0, and effect size pooling was performed in fixed- or random-effects models based on the results of I² and Q-test, and the surface under the cumulative ranking curve (SUCRA) was used for analysis to assess the cumulative probability of drug-induced PCOS. Publication bias was assessed by funnel plot Egger's test and meta regression.

Results

Twenty studies with a total of 1,524 patients were included in a single-arm analysis, which showed a combined effect size (95% CI) of 0.21 (0.15-0.28) for PCOS in patients taking anticonvulsant mood stabilizers. Nine controlled studies, including 500 patients taking medication and 457 healthy controls, were included in a meta-analysis, which showed OR = 3.23 and 95% CI = 2.19-4.76 for PCOS in women taking anticonvulsant mood stabilizers. Sixteen studies with a total of 1416 patients were included in a network meta-analysis involving four drugs, valproate (VPA), carbamazepine (CBZ), oxcarbazepine (OXC), and lamotrigine (LTG), and the results of the network meta-analysis showed that VPA (OR = 6.86, 95% CI = 2.92-24.07), CBZ (OR = 3.28, 95% CI = 0.99-12.64), OXC (OR = 4.30, 95% CI = 0.40-49.49), and LTG (OR = 1.99, 95% CI = 0.16-10.30), with cumulative probabilities ranked as VPA (90.1%), OXC (63.9%), CBZ (50.1%), and LTG (44.0%).

Conclusion

The incidence of PCOS was higher in female patients treated with anticonvulsant mood stabilizers than in the healthy population, with VPA having the highest likelihood of causing PCOS. The most recommended medication when considering PCOS factors is LTG.

Systematic review registration

identifier: CRD42022380927.

Non-opioid analgesics and post-operative pain following transoral robotic surgery for oropharyngeal cancer

Objective

To investigate associations between multimodal analgesia and post-operative pain among patients undergoing transoral robotic surgery for oropharyngeal squamous cell carcinoma.

Methods

Records of patients who underwent surgery from 5 September 2012 to 30 November 2016 were abstracted. Associations were assessed using multivariable analysis.

Results

A total of 216 patients (mean age of 59.1 years, 89.4 per cent male) underwent transoral robotic surgery (92.6 per cent were human papilloma virus positive, 87.5 per cent had stage T1–T2 tumours, and 82.9 per cent had stage N0–N1 nodes). Gabapentin (n = 86) was not associated with a reduction in severe pain. Ibuprofen (n = 72) was administered less often in patients with severe pain. Gabapentin was not associated with increased post-operative sedation (p = 0.624) and ibuprofen was not associated with increased bleeding (p = 0.221). Post-operative opioid usage was not associated with surgical duration, pharyngotomy, bilateral neck dissections, tumour stage, tumour size, subsite or gabapentin.

Conclusion

Scheduled low-dose gabapentin was not associated with improved pain control or increased respiratory depression. Ibuprofen was not associated with an increased risk of bleeding and may be under-utilised.

Data on the relationship between lamotrigine and levetiracetam serum/plasma levels and toxicity: Experience at an academic medical center

Lamotrigine and levetiracetam are second-generation anti-epileptic drugs used for the management of seizure disorders and some other medical conditions. In the related research article using retrospective data from an academic medical center, we analyzed 5046 samples originating from 1930 unique patients that had lamotrigine drug levels performed on serum/plasma and 4359 samples from 2451 patients that had levetiracetam drug levels performed. The data in this article provides the patient demographic, clinical location at time of drug level, and specific lamotrigine or levetiracetam serum/plasma drug level for all patients. For those instances with lamotrigine drug level greater than 14.0 mg/L or levetiracetam drug level of 80 mg/L or higher, additional data from chart review includes: indication for ordering the drug level, two main presenting signs or symptoms at time of drug level, timing of drug level (random, trough, peak, or unknown), changes in drug dosing following the drug level, concomitant therapy with valproic acid (lamotrigine only), and details related to drug overdose (if applicable). The analyzed data is provided in the supplementary tables included in this article. Volumes of test ordering by year is included in a figure. The dataset reported is related to the research article entitled "Correlation of Elevated Lamotrigine and Levetiracetam Serum/Plasma Levels with Toxicity: A Long-Term Retrospective Review at an Academic Medical Center" [K. E. Wood, K. L. Palmer, M.D. Krasowski, Correlation of elevated lamotrigine and levetiracetam serum/plasma levels with toxicity: A long-term retrospective review at an academic medical center, Toxicol. Rep. (2021) 8:1592-1598].

Carbamazepine Induces Platelet Apoptosis and Thrombocytopenia Through Protein Kinase A

Carbamazepine is extensively used worldwide to treat a wide range of disorders such as epilepsy, peripheral neuralgia and bipolar disorder. Thrombocytopenia and hemorrhage have been identified in multiple carbamazepine-treated patients. However, the underlying mechanism remains poorly understood. Here, we show that platelets undergo apoptosis after carbamazepine treatment. The apoptotic platelets induced by carbamazepine are rapidly removed in vivo, which accounts for thrombocytopenia. We found that carbamazepine treatment attenuates the phosphorylation level of bcl-xl/bcl-2-associated death promoter (BAD), vasodilator-associated stimulated phosphoprotein (VASP) and GPIbβ in platelets, indicating an inhibition effect on protein kinase A (PKA). We further demonstrated that carbamazepine reduced PKA activity through PI3K/Akt/PDE3A signaling pathway. Pharmacological activation of PKA or inhibition of PI3K/Akt/PDE3A protects platelets from apoptosis induced by carbamazepine. Importantly, PDE3A inhibitors or PKA activator ameliorates carbamazepine-mediated thrombocytopenia in vivo. These findings shed light on a possible mechanism of carbamazepine-induced thrombocytopenia, designating PDE3A/PKA as a potential therapeutic target in the treatment of carbamazepine-induced thrombocytopenia.

Correlation of elevated lamotrigine and levetiracetam serum/plasma levels with toxicity: A long-term retrospective review at an academic medical center

Lamotrigine and levetiracetam are widely used second-generation anti-epileptic drugs. Existing literature indicates that overdose of either drug is typically benign, but neurologic and cardiac toxicity can occur in some cases. In this retrospective study, we analyzed a large dataset of serum/plasma drug levels for lamotrigine and levetiracetam. The data covered 1,930 unique patients (5,046 levels) for lamotrigine and 2,451 patients (4,359 levels) for levetiracetam. We performed detailed chart review on all patients with one or more lamotrigine levels greater than 14.0 mg/L (293 unique patients) and all patients with one or more levetiracetam levels of 80 mg/L or higher (106 unique patients). No deaths directly attributable to lamotrigine or levetiracetam toxicity were reported. For cases with lamotrigine levels greater than 14.0 mg/L, the majority of patients were asymptomatic (55.3 %, n = 162). The most common presenting symptoms were ataxia (14.3 %, n = 42), seizures (14.0 %, n = 41), dizziness (11.9 %, n = 35), and altered mental status (11.6 %, n = 34). There were 12 overdoses (11 intentional) involving lamotrigine, all of which presented with either altered mental status (n = 8) or seizures (n = 4). The highest estimated dose reportedly ingested was 20 g. Cardiac toxicity was observed in two cases involving intentional overdose of lamotrigine. For patients with levetiracetam serum/plasma levels of 80 mg/L or higher, 48 patients (45.3 %) were asymptomatic. Symptomatic patients most commonly presented with seizures (31.1 %, n = 33) and altered mental status (15.1 %, n = 16), and none showed cardiac symptoms. There were only two cases involving intentional levetiracetam overdose, one of which presented with altered mental status after ingestion of 45 g and the other asymptomatic after ingestion of 6 g. Overall, our data is consistent with previous investigations that lamotrigine and levetiracetam toxicity most typically presents with neurologic symptoms and rarely cardiac arrhythmias. Approximately half of the patients with elevated lamotrigine or levetiracetam drug levels are asymptomatic.

Voltage gated sodium channel inhibitors as anticonvulsant drugs: A systematic review on recent developments and structure activity relationship studies

Voltage-gated sodium channel blockers are one of the vital targets for the management of several central nervous system diseases, including epilepsy, chronic pain, psychiatric disorders, and spasticity. The voltage-gated sodium channels play a key role in controlling cellular excitability. This reduction in excitotoxicity is also applied to improve the symptoms of epileptic conditions. The effectiveness of antiepileptic drugs as sodium channel depends upon the reversible blocking of the spontaneous discharge without blocking its propagation. There are number of antiepileptic drug(s) which are in pipeline to flour the market to conquer abnormal neuronal excitability. They inhibit the seizures through the inhibition of complex voltage- and frequency-dependent ionic currents through sodium channels. Over the past decade, the sodium channel is one of the most explored targets to control or treat the seizure, but there has not been any game-changing discovery yet. Although there are large numbers of drugs approved for the treatment of epilepsy, however they are associated with several acute to chronic side effects. Many research groups have tirelessly worked for better therapeutic medication on this popular target to treat epileptic seizures. The review quotes briefly the developments of the approved examples of sodium channel blockers as anticonvulsant drugs. Medicinal chemists have tried the design and development of some more potent anticonvulsant drugs to minimize the toxicity that are discussed here, and an emphasis is given for their possible mechanism and the structure-activity relationship (SAR).

PI3K, mTOR and GSK3 modulate cytokines' production in peripheral leukocyte in temporal lobe epilepsy

INTRODUCTION

Epilepsy is a common pathological condition that predisposes individuals to seizures, as well as cognitive and emotional dysfunctions. Different studies have demonstrated that inflammation contributes to the pathophysiology of epilepsy. Indeed, seizures change the peripheral inflammatory pattern, which, in turn, could contribute to seizures. However, the cause of the altered production of peripheral inflammatory mediators is not known. The PI3K/mTOR/GSK3β pathway is important for different physiological and pharmacological phenomena. Therefore, in the present study, we tested the hypothesis that the PI3K/mTOR/GSK3β pathway is deregulated in immune cells from patients with epilepsy and contributes to the abnormal production of inflammatory mediators.

METHODS

Patients with temporal lobe epilepsy presenting hippocampal sclerosis and controls aged between 18 and 65 years-old were selected for this study. Peripheral blood was collected for the isolation of peripheral mononuclear blood cells (PBMC). Cells were pre-incubated with different PI3K, mTOR and GSK-3 inhibitors for 30 min and further stimulated with phytohaemaglutinin (PHA) or vehicle for 24 h. The supernatant was used to evaluate the production of IL-1β, IL-6, IL-10, TNF e IL-12p70.

RESULTS

Non-selective inhibition of PI3K, as well as inhibition of PI3Kγ and GSK-3, reduced the levels of TNF and IL-10 in PHA-stimulated cells from TLE individuals. This stimulus increased the production of IL-12p70 only in cells from TLE individuals, while the inhibition of PI3K and mTOR enhanced the production of this cytokine. On the other hand, inhibition of GSK3 reduced the PHA-induced production of IL-12p70.

CONCLUSIONS

Herein we demonstrated that the production of cytokines by immune cells from patients with TLE differs from non-epileptic patients. This differential regulation may be associated with the altered activity and responsiveness of intracellular molecules, such as PI3K, mTOR and GSK-3, which, in turn, might contribute to the inflammatory state that exists in epilepsy and its pathogenesis.

High performance liquid chromatography: A versatile tool for assaying antiepileptic drugs in biological matrices

Epilepsy is a recurrent long-term illness occurring in approximately 1.0% of the world's population. There are currently about 29 approved antiepileptic drugs for the management of epilepsy. Due to narrow therapeutic indices of most antiepileptic drugs, clinical pharmacokinetic characteristics and therapeutic drug monitoring of these drugs are imperative. The objectives of this review were to identify common chromatographic principles, requirements and/or conditions for high-performance liquid chromatography as applied to assay of antiepileptic drugs in biological matrices. The review was conducted using 66 peer reviewed articles (1990 to 2020) from 29 journals that were sought via PubMed, Science Direct and Google Scholar. In all, 29 antiepileptic drugs were assayed from 6 different biological matrices. Forty-three of the reviewed articles estimated the concentration of only one antiepileptic drug, whilst 23 articles focused on simultaneous determination of two or more antiepileptic drugs. Thirty-four, 20, and 14 articles reported using liquid-liquid extraction, protein precipitation, or solid phase extraction for sample clean up, respectively. The ratio of reversed-phase to normal phase, LC-UV to LC-MS and isocratic elution to gradient elution were 61:3, 43:7 and 55:11, respectively. With the exception of one article the reported recoveries ranged from 60.3% to 109.6%. It is noteworthy, that, the performance metrics of high-performance liquid chromatography are better compared to other assays of antiepileptic drugs in biological matrices. This review describes the relevant liquid chromatographic method conditions over the past 30 years for the analysis of this class of drugs, which provides a basis for further method development and optimization.

Synthesis, in silico, in vitro and in vivo evaluations of isatin aroylhydrazones as highly potent anticonvulsant agents

In this study, a series of new isatin aroylhydrazones (5a-e and 6a-e) was synthesized and evaluated for their anticonvulsant activities. The (Z)-configuration of compounds was confirmed by ¹H NMR. In vivo studies using maximal electroshock (MES) and pentylenetetrazole (PTZ) models of epilepsy in mice revealed that while most of compounds had no effect on chemically-induced seizures at the higher dose of 100 mg/kg but showed significant protection against electrically-induced seizures at the lower dose of 5 mg/kg. Certainly, N-methyl analogs 6a and 6e were found to be the most effective compounds, displaying 100% protection at the dose of 5 mg/kg. Protein binding and lipophilicity(logP) of the selected compounds (6a and 6e) were also determined experimentally. In silico evaluations of title compounds showed acceptable ADME parameters, and drug-likeness properties. Distance mapping and docking of the selected compounds with different targets proposed the possible action of them on VGSCs and GABA_A receptors. The cytotoxicity evaluation of 6a and 6e against SH-SY5Y and Hep-G2 cell lines indicated safety profile of compounds on the neuronal and hepatic cells.

[The efficacy and tolerability of extended release carbamazepine in adult patients with new-onset epilepsy using epileptiform activity index]

OBJECTIVE

To evaluate the efficacy and tolerability of extended release carbamazepine (finlepsin-retard and tegretol CR) in adult patients with new-onset focal epilepsy (FE) with the assessment of epileptiform activity index (EAI).

MATERIAL AND METHODS

The study included 62 patients (38 (61.3%) men and 24 (38.7%) women) with new-onset FE aged ≥18 years (mean age 42.9±18.4 years). All patients underwent video-ECG-monitoring with EAI assessment at each visit. Treatment efficacy was assessed using the criteria of seizure absence (medically induced remission), seizure rate decrease by >50% (responders), seizure rate decrease by <50% - insufficient efficacy, retention on treatment and seizure rate increase compared to baseline and/or development of new type of seizures (aggravation). Overall study period was 12 months.

RESULTS

By the end of the 12-month follow-up period, there was a 4.3-fold decrease of the total EAI compared to baseline (p<0.001). Retention on carbamazepine treatment during 12 months was achieved in 61.3% (n=38) patients; medically induced remission - in 40.3% (n=25); seizure rate decrease by >50% - in 21.0% (n=13). In 29.1% (n=18) of patients, treatment change was performed; double-drug therapy, including carbamazepine, was prescribed in 9.6% (n=6) of patients. Incidence of adverse events was 29.1% (n=18).

CONCLUSIONS

Carbamazepine is an effective and promising drug for initial monotherapy of FE. Its use in the treatment of FE results in a 4.3-fold decrease of EAI (p<0.001), which reflects the efficacy of treatment. EAI is an additional objective measure of treatment efficacy.

Multipronged Attack of Stem Cell Therapy in Treating the Neurological and Neuropsychiatric Symptoms of Epilepsy

Epilepsy stands as a life-threatening disease that is characterized by unprovoked seizures. However, an important characteristic of epilepsy that needs to be examined is the neuropsychiatric aspect. Epileptic patients endure aggression, depression, and other psychiatric illnesses. Therapies for epilepsy can be divided into two categories: antiepileptic medications and surgical resection. Antiepileptic drugs are used to attenuate heightened neuronal firing and to lessen seizure frequency. Alternatively, surgery can also be conducted to physically cut out the area of the brain that is assumed to be the root cause for the anomalous firing that triggers seizures. While both treatments serve as viable approaches that aim to regulate seizures and ameliorate the neurological detriments spurred by epilepsy, they do not serve to directly counteract epilepsy's neuropsychiatric traits. To address this concern, a potential new treatment involves the use of stem cells. Stem cell therapy has been employed in experimental models of neurological maladies, such as Parkinson's disease, and neuropsychiatric illnesses like depression. Cell-based treatments for epilepsy utilizing stem cells such as neural stem cells (NSCs), mesenchymal stem cells (MSCs), and interneuron grafts have been explored in preclinical and clinical settings, highlighting both the acute and chronic stages of epilepsy. However, it is difficult to create an animal model to capitalize on all the components of epilepsy due to the challenges in delineating the neuropsychiatric aspect. Therefore, further preclinical investigation into the safety and efficacy of stem cell therapy in addressing both the neurological and the neuropsychiatric components of epilepsy is warranted in order to optimize cell dosage, delivery, and timing of cell transplantation.

Therapeutic Drug Monitoring of Second- and Third-Generation Antiepileptic Drugs: Insights From a College of American Pathologists Proficiency Testing Survey

CONTEXT.—

Therapeutic drug monitoring has traditionally been widely used for first-generation antiepileptic drugs (AEDs) such as carbamazepine and phenytoin. The last 2 decades have seen the introduction of second- and third-generation AEDs (eg, lamotrigine, levetiracetam, and topiramate) into clinical practice.

OBJECTIVE.—

To use data from the College of American Pathologists Therapeutic Drug Monitoring, Extended proficiency testing survey to determine the performance of assays used for therapeutic drug monitoring of newer AEDs, including comparison of enzyme immunoassay and chromatographic techniques.

DESIGN.—

Six years of proficiency testing surveys were reviewed (2013-2018).

RESULTS.—

Steady growth was seen in participant volumes for newer AEDs. The analytical performance of automated enzyme immunoassays for lamotrigine, levetiracetam, and topiramate was similar to that of chromatographic methods, consistent with published literature using patient samples for comparisons. The majority of participating laboratories now use enzyme immunoassays to measure levetiracetam.

CONCLUSIONS.—

Survey results reflect steadily growing interest in therapeutic drug monitoring of newer AEDs. The increasing availability of robust immunoassays for new AEDs should facilitate their clinical utility, especially for clinical laboratories that do not perform chromatographic assays for therapeutic drug monitoring.

Schiff Bases of Isatin and Adamantane-1-Carbohydrazide: Synthesis, Characterization and Anticonvulsant Activity

Epilepsy is the most common neurological condition and cause of substantial morbidity and mortality. In the present study, the molecular hybridization tool was adopted to obtain six Schiff bases of isatin and adamantane-1-carbohydrazide (18–23). Then, their anticonvulsant activity was evaluated using pentylenetetrazole- (PTZ-) induced seizure model using phenobarbitone as a positive control. Our findings showed that compounds 18–23 provided significant protection against PTZ-induced seizure, and maximum activities were associated with compound 23. Moreover, all investigated compounds increased the latency of induced convulsion and reduced the duration of epilepsy with compound 23 being the best. Interestingly, most of the synthesized molecules showed reduction in neurological symptoms and severity of the seizure. Molecular docking studies suggest GABA-A receptor as a potential target, and in silico ADME screening revealed that the pharmaceutical properties of compound 23 are within the specified limit. Thus, compound 23 was identified as a promising candidate that warrants further drug discovery processes.

Valproic Acid and Its Amidic Derivatives as New Antivirals against Alphaherpesviruses

Herpes simplex viruses (HSVs) are neurotropic viruses with broad host range whose infections cause considerable health problems in both animals and humans. In fact, 67% of the global population under the age of 50 are infected with HSV-1 and 13% have clinically recurrent HSV-2 infections. The most prescribed antiherpetics are nucleoside analogues such as acyclovir, but the emergence of mutants resistant to these drugs and the lack of available vaccines against human HSVs has led to an imminent need for new antivirals. Valproic acid (VPA) is a branched short-chain fatty acid clinically used as a broad-spectrum antiepileptic drug in the treatment of neurological disorders, which has shown promising antiviral activity against some herpesviruses. Moreover, its amidic derivatives valpromide and valnoctamide also share this antiherpetic activity. This review summarizes the current research on the use of VPA and its amidic derivatives as alternatives to traditional antiherpetics in the fight against HSV infections.

Efficacy and tolerability of perampanel as a first add-on therapy with different anti-seizure drugs

PURPOSE

To investigate the efficacy and tolerability of perampanel (PER) when administered as a first add-on therapy to patients with focal epilepsy or idiopathic generalized epilepsy (IGE) taking one other antiseizure drug (ASD).

METHODS

This multicentre, retrospective, one-year observational study collected data from patients (≥12 years) who initiated treatment with PER as first add-on therapy. Patients had to be experiencing inadequate seizure control on ASD monotherapy and tried ≤3 ASD monotherapies before initiating PER. Multivariate logistic regression analyses were performed, adjusted for the number and type of previous seizures, duration and aetiology of epilepsy.

RESULTS

Of the 149 patients included in the study (mean age 41 years; 54.4 % male), 118 (79.2 %) were still receiving PER as first add-on treatment after 12 months. Mean PER dose was 6.2 mg/day. At 12 months, 45.6 % were seizure-free and 84.6 % responders. A significant difference in seizure freedom rate was found between patients with IGE and patients with focal epilepsy, but not in responders. Reduced seizure control was observed when PER was administered with strong enzyme-inducing ASDs; conversely, increased seizure control was seen when the same dose of PER was combined with enzyme-inhibiting ASDs. The most frequent adverse events were dizziness (15.4 %), irritability (14.1 %) and drowsiness (14.1 %); no differences in tolerance were observed among different combinations.

CONCLUSION

PER demonstrated a good efficacy and safety profile when used as a first add-on therapy in patients who did not respond to monotherapy. PER dose adjustments may optimize seizure control when combined with strong enzyme-inducing or enzyme-inhibiting ASDs.

Recent advancement in the discovery and development of anti-epileptic biomolecules: An insight into structure activity relationship and Docking

Although there have been many advancements in scientific research and development, the cause of epilepsy still remains an open challenge. In spite of high throughput research in the field of anti-epileptic drugs, efficacy void is still prevalent before the researchers. Researchers have persistently been exploring all the possibilities to curb undesirable side effects of the anti-epileptic drugs or looking for a more substantial approach to diminish or cure epilepsy. The drug development has shown a hope to medicinal chemists and researchers to carry further research by going through a substantial literature survey. This review article attempts to describe the recent developments in the anti-epileptic agents, pertaining to different molecular scaffolds considering their structure-activity relationship, docking studies and their mechanism of actions.

Development of novel indole-linked pyrazoles as anticonvulsant agents: A molecular hybridization approach

A series of 3-{2-[1-acetyl-5-(substitutedphenyl)-4,5-dihydropyrazol-3-yl]hydrazinylidene}-1,3-dihydro-2H-indol-2-ones 24-43 was synthesized using an appropriate synthetic route and evaluated experimentally by the maximal electroshock test. These compounds were evaluated for antidepressant and antianxiety activities. The most active compound, 3-{2-[1-acetyl-5-(4-chlorophenyl)-4,5-dihydropyrazol-3-yl]hydrazinylidene}-1,3-dihydro-2H-indol-2-one 25, exhibited an ED₅₀ of 13.19 mmol/kg, a TD₅₀ of 43.49 mmol/kg, and a high protective index of 3.29, compared with the standard drug diazepam. To get insights into the intermolecular interactions, molecular docking studies were performed at the active site of the GABA_A receptor and the MAO-A enzyme. Molecular docking studies are also in agreement with the pharmacological evaluation with potent compounds, exhibiting docking scores of -1.5180 and 0.7458 for the GABA_A receptor and MAO-A, respectively. The 3D-QSAR analysis was carried out by Vlife MDS engine 4.3.1, and a statistically reliable model with good predictive power (r²  = 0.7523, q²  = 0.3773) was achieved. The 3D-QSAR plots gave insights into the structure-activity relationship of these compounds, which may aid in the design of potent benzopyrrole derivatives as anticonvulsant agents. So, our research can make a great impact on those medicinal chemists who work on the development of anticonvulsant agents.

Novel 3-Substituted-2, 3-Dihydro-2-Thioxoquinazolin-4-(1H)-one derivative as Anticonvulsants: Synthesis, Molecular Docking and Pharmacological Screening

Background:

According to the World Health Organization, 50 million people worldwide are suffering from epilepsy, making it one of the most common neurological diseases globally. 2,3 disubstituted quinazolinone-4-one derivatives endowed with various pharmacological activity, particularly having anticonvulsant action.

Objectives:

The aim of this study was to synthesize 3-Substituted-2,3-Dihydro-2-thioxoquinazolin- 4-(1H)-one derivative and evaluate for anticonvulsant activity and neurotoxicity in order to find an efficient, compound with lesser side effects.

Methods:

A novel series of 3-[4-(2-amino-5, 6-dihydro-4(substituted phenyl)-4H-1, 3-oxazin /thiazin-6yl) phenyl]-2, 3-dihyro-2-thioxoquinazolin-4(1H)-one derivatives (4a-4p) were synthesized. The structures of the synthesized compounds were assigned on the basis of spectral data (UV, IR, 1HNMR, 13CNMR and MS) and performed anticonvulsant activity against maximal electroshock test and Subcutaneous Pentylenetetrazole model. Neurotoxicity was assessed using a rotarod apparatus test. The molecular docking study was performed to assess their binding affinities towards Gamma-Aminobutyric Acid type A receptor. A quantitative estimate of drug-likeness was also performed, which calculates the molecular properties and screen the molecules based on drug-likeness rules.

Results:

Compounds 4b, 4e, 4j and 4m have shown the highest anticonvulsant activity against tonic seizure with decreased mean duration of tonic hind leg extension of 8.31, 7.35, 8.61 and 8.99 s, respectively in maximal electroshock model and increased onset time clonic convulsion duration of 94.45, 96.65, 93.51 and 91.86 s in Subcutaneous Pentylenetetrazole model. Molecular docking study revealed a better binding affinity with Gamma-Aminobutyric Acid type A receptor.

Conclusion:

The compound 4b and 4e emerged out as the pilot molecule with a better anticonvulsant activity without any neurotoxicity. The obtained results showed that compounds 4b and 4e could be useful as a template for future design, optimization, and investigation to produce more active analogs.

Novel treatment approaches and pediatric research networks in status epilepticus

This paper contains five contributions which were presented as part of the novel therapies section of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures. These illustrate recent advances being made in the management and therapy of status epilepticus. The five contributions concern: genetic variations in Na + channel genes and their importance in status epilepticus; the European Reference Network for rare and complex epilepsies EpiCARE; the North American Pediatric Status Epilepticus Research Group (pSERG); Fenfluramine as a potential therapy for status epilepticus' and the valproate derivatives, valnoctamide and sec-butylpropylacetamide (SPD), as potential therapies for status epilepticus. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

Comparative neuropsychological effects of carbamazepine and eslicarbazepine acetate

People with epilepsy are at increased risk for neuropsychological dysfunction due to multiple factors, of which the most amendable are antiseizure medications (ASMs). Antiseizure medication effectiveness is frequently determined by tolerability. In this study, we compared the neuropsychological effects of eslicarbazepine acetate (ESL) and carbamazepine immediate-release (CBZ) using a randomized, double-blind, crossover design in healthy volunteers with a 2-week titration and 4-week maintenance phase in each treatment arm (CBZ = 400 mg BID and ESL = 800 mg qAM). Neuropsychological testing was performed at the initial visit, repeated at 1st baseline nondrug condition, end treatment #1, 2nd nondrug condition one month after treatment #1, end treatment #2, and 3rd nondrug condition one month after treatment #2. Neuropsychological testing was conducted 2 h after morning dose and included computer (i.e., dual task test, selective attention test, symbol digit, verbal memory, visuospatial memory, and 1- & 2-back continuous performance) and noncomputer tasks (i.e., Medical College of Georgia (MCG) paragraph memory, Stroop, Symbol Digit Modalities Test, Profile of Mood States). z-Scores calculated from nondrug conditions were used to compare ESL and CBZ for the 23 completers. Follow-up analyses included individual test scores and distribution of individual raw means. Mean blood levels on test day were CBZ = 8.9 μg/ml and ESL = 15.3 μg/ml. Omnibus z-score was significantly better for ESL (p = .0001). For individual measures, executive function and selective attention tests were statistically significantly better for ESL. Individual test raw means favored ESL over CBZ on 22 of 30 measures (p = .016, 2-tailed sign test). Eslicarbazepine acetate demonstrated less adverse neuropsychological effects than CBZ.

QSAR characterization of new synthesized hydantoins with antiproliferative activity

Hydantois have been identified as constituents of a number of pharmacologically active molecules. In the present study, we have examined in vitro antiproliferative activity against human colon cancer cell lines HCT-116 of three series of 3-(4-substituted benzyl)-hydantoins with various substituent attached in position 5 of the hydantoin ring. Since the investigated compounds have recently been synthesized and show antiproliferative activity, a good understanding of the properties of the potential drug responsible for their pharmacokinetics is an important goal for their further development. One of the important properties is lipophilicity. Lipophilicity has been assessed by reversed-phase liquid chromatography (high-performance thin-layer chromatography and high-pressure liquid chromatography) by means of direct and indirect (using calibration curve) methods. Chromatographic lipophilicity indices in addition to calculated logP values were compared by hierarchical cluster analysis. The linear solvation energy relationship approach was used to understand and compare the types and relative strength of the molecular interactions that occur in the chromatographic as well as in the n-octanol-water partitioning systems. Finally, correlation between in silico pharmacokinetic predictors and antiproliferative activity was examined. Preliminary quantitative structure-activity relationship modeling indicates that pharmacokinetic predictors capture only one-quarter of all chemical features that are important for antiproliferative activity itself. Among selected descriptors are chromatographic lipophilicity indices.

Teratogenicity of valproic acid and its constitutional isomer, amide derivative valnoctamide in mice

OBJECTIVES

The anticonvulsant valproic acid (VPA) has a known teratogenic effect capable of inducing major congenital malformations and developmental disorders. A comparative teratogenicity study of VPA and its analog valnoctamide (VCD), which is a new generation candidate antiepileptic drug, was carried out using Swiss Vancouver (SWV) mice.

METHODS

Pregnant SWV dams were treated with either a single intraperitoneal injection of VPA (1.8 and 2.7 mmol/kg), VCD (1.8 and 2.7 mmol/kg), or vehicle on E8:12 (gestational day:hour). The numbers of implantation and resorption, viable and dead fetuses, and the presence of gross fetal visceral and skeletal abnormalities were determined (E18). Real-time Polymerase chain reaction (RT-PCR) arrays were used to analyze the expression of 84 genes related to the processes of neurogenesis and neural stem cell differentiation.

RESULTS

Significant decreases in pregnancy weight gain and the number of live fetuses were observed when VPA was administered at the high dose, whereas the percentage of exencephalic fetuses was significantly increased in VPA treated compared with an equivalent VCD dosage group. There was a dose-related increase in visceral defects in the VPA-exposed fetuses. Missing skull bones and fused vertebrae in fetuses occurred at the high dose of VPA. Three genes (Mtap2, Bmp8b, and Stat3) were significantly upregulated and one (Heyl) was downregulated in samples from VPA-treated dams.

CONCLUSIONS

The study demonstrates that the teratogenicity of VPA was significantly greater than that of an equimolar dose of VCD. Four genes (Mtap2, Bmp8b, Stat3, and Heyl) represent candidate target genes for the underlying teratogenic mechanism responsible for VPA-induced malformations.

Microextraction combined with microderivatization for drug monitoring and protein modification analysis from limited blood volume using mass spectrometry

In the clinic, ethosuximide is commonly used to treat generalized absence seizures but has recently been repurposed for other diseases. Because of adverse effects and drug interactions, high-throughput therapeutic drug monitoring of ethosuximide is necessary. Microextraction is a simple, effective, rapid, and low consumption of organic solvents method for sample preparation. In this study, microderivatization-increased detection (MDID)-combined microextraction was used to detect ethosuximide by mass spectrometry. Ethosuximide is a difficult to retain and ionize compound in the C18 nano-flow column and ionization interface, respectively. Hence, we developed a fast method for detecting ethosuximide in human plasma by using the MDID strategy (within 2 min). Chemical microderivatization parameters were studied and optimized to increase the sensitivity of ethosuximide detection at trace levels. The linear range for the analysis of ethosuximide in 10 μL plasma was 5-500 μg/mL with a coefficient of determination (r²) ≥ 0.995. The precision and accuracy of intraday and interday analyses of ethosuximide were below 13.0%. Furthermore, modifications of major proteins in plasma and blood cells, induced by ethosuximide, were identified. The proposed method effectively utilizes microliter samples to detect drug plasma concentrations under suitable microextraction procedures toward the eco-friendly goal of low consumption of organic solvents. Graphical abstract ᅟ.

Design and synthesis of novel anti-hyperalgesic agents based on 6-prenylnaringenin as the T-type calcium channel blockers

Since 6-prenylnaringenin (6-PNG) was recently identified as a novel T-type calcium channel blocker with the IC₅₀ value around 1 µM, a series of flavanone derivatives were designed, synthesized and subsequently evaluated for T-channel-blocking activity in HEK293 cells transfected with Ca_v3.2 T-type channels using a patch-clamp technique. As a result, several new flavanones blocked Ca_v3.2-dependent T-currents more potently than 6-PNG. In the synthesized compounds, 6-(3-ethylpent-2-enyl)-5,7-dihydroxy-2-(2-hydroxyphenyl)chroman-4-one 8j, 6-(3-ethylpent-2-enyl)-5,7-dihydroxy-2-(4-hydroxyphenyl)chroman-4-one 11b, 6-(2-cyclopentylideneethyl)-5,7-dihydroxy-2-(4-hydroxyphenyl)chroman-4-one 11d, and 6-(2-Cyclopentylethyl)-5,7-dihydroxy-2-(4-hydroxyphenyl)chroman-4-one 12c were more potent blocker than 6-PNG with the IC₅₀ value of 0.39, 0.26, 0.46, and 0.50 µM, respectively. Among the above four derivatives, the compound 8j provided the best result in the in vivo experiments; i.e. systemic administration of 8j at the minimum dose completely restored neuropathic pain induced by partial sciatic nerve ligation in mice.

Carbamazepine adverse drug reactions

INTRODUCTION

Carbamazepine (CBZ) is used for the treatment of epilepsy and other neurological and psychiatric disorders. The occurrence of adverse reactions (ADRs) to CBZ can negatively impact the quality of life of patients, as well as increase health-care costs. Thus, knowledge of CBZ-induced ADRs is important to achieve safer treatment outcomes. Areas covered: This review describes the clinical features, known mechanisms, and clinical management of the main CBZ-induced ADRs. In addition, pharmacogenetic studies focused on ADRs induced by CBZ are cited. Expert commentary: CBZ-induced ADRs are well known in the literature. The metabolite CBZ-10,11-epoxide plays an important role in the mechanism that underlies the ADRs induced by CBZ. Several factors should be considered for a safer use of CBZ, such as monotherapy prescription when possible, an adequate dose titration, knowledge of previous ADRs in the patient, and routine monitoring of CBZ plasma concentrations in symptomatic patients. Pharmacogenetics is a potential tool for CBZ therapy improvement, and the design of multicenter studies focused on the identification of biomarkers for CBZ-induced ADRs could provide useful information for a safer CBZ therapy.

Supramolecular architectures of succinates of 1-hydroxypropan-2-aminium derivatives

Aminoalkanol and aroxyalkyl derivatives are known as potential anticonvulsants. Two new salts, namely bis{(R,S)-N-[2-(2,6-dimethylphenoxy)ethyl]-1-hydroxypropan-2-aminium} succinate (1s), C13H22NO2 +·0.5C4H4O4 2−, and bis{(S)-(+)-N-[2-(2,6-dimethylphenoxy)ethyl]-1-hydroxypropan-2-aminium} succinate (2s), C13H22NO2 +·0.5C4H4O4 2−, have been prepared and characterized by single-crystal X-ray diffraction. The N atoms are protonated by proton transfer from succinic acid. Salt 1s crystallizes in the space group P21/n with one cation and half an anion in the asymmetric unit across an inversion centre, while (2s) crystallizes in the space group P21 with four cations and two anions in the asymmetric unit. The hydroxy group of the cation of 1s is observed in two R/S disorder positions. The crystals of these two salts display similar supramolecular architectures (i.e. two-dimensional networks), built mainly by intermolecular N+—H...Oδ− and O—H...Oδ− hydrogen bonds, where `δ−' represents a partial charge. The succinate anions are engaged in hydrogen bonds, not only with protonated N atoms, but also with hydroxy groups.

Cinnamamide pharmacophore for anticonvulsant activity: evidence from crystallographic studies

A number of cinnamamide derivatives possess anticonvulsant activity due to the presence of a number of important pharmacophore elements in their structures. In order to study the correlations between anticonvulsant activity and molecular structure, the crystal structures of three new cinnamamide derivatives with proven anticonvulsant activity were determined by X-ray diffraction, namely (R,S)-(2E)-N-(2-hydroxybutyl)-3-phenylprop-2-enamide-water (3/1), C₁₃H₁₇NO₂·0.33H₂O, (1), (2E)-N-(1-hydroxy-2-methylpropan-2-yl)-3-phenylprop-2-enamide, C₁₃H₁₇NO₂, (2), and (R,S)-(2E)-N-(1-hydroxy-3-methyl-butan-2-yl)-3-phenylprop-2-enamide, C₁₄H₁₉NO₂, (3). Compound (1) crystallizes in the space group P-1 with three molecules in the asymmetric unit, whereas compounds (2) and (3) crystallize in the space group P2₁/c with one and two molecules, respectively, in their asymmetric units. The carbonyl group of (2) is engaged in an intramolecular hydrogen bond with the hydroxy group. This type of interaction is observed for the first time in these kinds of derivatives. A disorder of the substituent at the N atom occurs in the crystal structures of (2) and (3). The crystal packing of all three structures is dominated by a network of O-H...O and N-H...O hydrogen bonds, and leads to the formation of chains and/or rings. Furthermore, the crystal structures are stabilized by numerous C-H...O contacts. We analyzed the molecular structures and intermolecular interactions in order to propose a pharmacophore model for cinnamamide derivatives.

Valnoctamide: The effect on relieving of neuropathic pain and possible mechanisms

The purpose of this study is to assess the possible anti-allodynic and antihyperalgesic effect of valnoctamide, an amide derivative of valproic acid, at the doses of 40, 70 and 100 mg/kg (i.p.) in neuropathic pain model induced by chronic constriction injury in rats, by using dynamic plantar test and plantar test (Hargreaves method), and to evaluate that the possible role of certain serotonin, noradrenergic, opioid and GABAergic receptors by pre-treatment with 1 mg/kg (i.p.) ketanserin, yohimbine, naloxone and 0.5 mg/kg (i.p.) bicuculline, respectively. 70 and 100 mg/kg valnoctamide significantly increased the mechanical and thermal thresholds decreasing with the development of neuropathy and demonstrated anti-allodynic and antihyperalgesic activity. Limited contribution of serotonin 5-HT_2A/2C receptors and α2-adrenoceptors, and significant contribution of GABA_A and opioid receptors to the anti-allodynic activity have been identified whereas remarkable contribution of opioid receptors and significant contribution of serotonin 5-HT_2A/2C receptors, α2-adrenoceptors, GABA_A receptors to the antihyperalgesic activity have been identified. Based upon these findings and considering that valnoctamide has safer side-effect profile, it is possible to say that valnoctamide is a potential agent that might be used alone or in combination with the other effective therapies in the alleviating of neuropathic pain.

Mitochondrial Liver Toxicity of Valproic Acid and Its Acid Derivatives Is Related to Inhibition of &#945;-Lipoamide Dehydrogenase

The liver toxicity of valproic acid (VPA) is an established side effect of this widely used antiepileptic drug, which is extremely problematic for patients with metabolic epilepsy and particularly epilepsy due to mitochondrial dysfunction. In the present report, we investigated the reason for liver mitochondrial toxicity of VPA and several acid and amide VPA analogues. While the pyruvate and 2-oxoglutarate oxidation rates of rat brain mitochondria were nearly unaffected by VPA, rat liver mitochondrial pyruvate and 2-oxoglutarate oxidation was severely impaired by VPA concentrations above 100 µM. Among the reactions involved in pyruvate oxidation, pyruvate transport and dehydrogenation steps were not affected by VPA, while &#945;-lipoamide dehydrogenase was strongly inhibited. Strong inhibition of &#945;-lipoamide dehydrogenase was also noted for the VPA one-carbon homolog sec -butylpropylacetic acid (SPA) and to a lesser extent for the VPA constitutional isomer valnoctic acid (VCA), while the corresponding amides of the above three acids valpromide (VPD), sec -butylpropylacetamide (SPD) and valnoctamide (VCD) showed only small effects. We conclude that the active inhibitors of pyruvate and 2-oxoglutarate oxidation are the CoA conjugates of VPA and its acid analogues affecting selectively &#945;-lipoamide dehydrogenase in liver. Amide analogues of VPA, like VCD, show low inhibitory effects on mitochondrial oxidative phosphorylation in the liver, which might be relevant for treatment of patients with mitochondrial epilepsy.

Design and Comparative Evaluation of the Anticonvulsant Profile, Carbonic-Anhydrate Inhibition and Teratogenicity of Novel Carbamate Derivatives of Branched Aliphatic Carboxylic Acids with 4-Aminobenzensulfonamide

Epilepsy is one of the most common neurological diseases, with between 34 and 76 per 100,000 people developing epilepsy annually. Epilepsy therapy for the past 100⁺ years is based on the use of antiepileptic drugs (AEDs). Despite the availability of more than twenty old and new AEDs, approximately 30% of patients with epilepsy are not seizure-free with the existing medications. In addition, the clinical use of the existing AEDs is restricted by their side-effects, including the teratogenicity associated with valproic acid that restricts its use in women of child-bearing age. Thus, there is an unmet clinical need to develop new, effective AEDs. In the present study, a novel class of carbamates incorporating phenethyl or branched aliphatic chains with 6-9 carbons in their side-chain, and 4-benzenesulfonamide-carbamate moieties were synthesized and evaluated for their anticonvulsant activity, teratogenicity and carbonic anhydrase (CA) inhibition. Three of the ten newly synthesized carbamates showed anticonvulsant activity in the maximal-electroshock (MES) and 6 Hz tests in rodents. In mice, 3-methyl-2-propylpentyl(4-sulfamoylphenyl)carbamate(1), 3-methyl-pentan-2-yl-(4-sulfamoylphenyl)carbamate (9) and 3-methylpentyl, (4-sulfamoylphenyl)carbamate (10) had ED₅₀ values of 136, 31 and 14 mg/kg (MES) and 74, 53, and 80 mg/kg (6 Hz), respectively. Compound (10) had rat-MES-ED₅₀ = 13 mg/kg and ED₅₀ of 59 mg/kg at the mouse-corneal-kindling test. These potent carbamates (1,9,10) induced neural tube defects only at doses markedly exceeding their anticonvuslnat-ED₅₀ values. None of these compounds were potent inhibitors of CA IV, but inhibited CA isoforms I, II and VII. The anticonvulsant properties of these compounds and particularly compound 10 make them potential candidates for further evaluation and development as new AEDs.